The present invention relates generally to linkage systems. More particularly, the invention relates to a linkage system for the windshield wiper which is strong, lightweight and readily adaptable to a variety of different windshield wiper configurations.
The automotive windshield wiper system typically consists of an actuator motor (either electric, air or hydraulic) coupled through suitable linkage to a pivot assembly which in turn drives the wiper arms and blades. Conventionally, the actuator motor is disposed in a suitable location usually in the engine compartment near the windshield. The pivot assemblies are likewise disposed adjacent the lower edge of the windshield and transmit motion of the motor to the wiper arms. The desired wipe angle and the cleaning area on the windshield are obtained by properly selecting the length and configuration of the linkage and of the wiper arms attached to the shaft of the pivot assembly. In most applications two arms and blades are actuated by a single motor through the use of two or more connecting links. These connecting links are therefore an important component of most windshield wiper systems.
There are numerous different automotive body styles and correspondingly numerous different windshield wiper systems and configurations. Conventionally, the windshield wiper linkage has consisted of one or more links made of flat stamped steel members or steel conduit tubing. To accommodate the variation in sizes and geometries of different wiper systems it has often been necessary to re-engineer and retool the linkage with each wipe system design change. Thus, traditionally, there has been very little opportunity for standardization of the linkage components. The lack of standardization adds to the overall cost of the vehicle, since the tooling, manufacturing and inventory costs are all increased by the need to maintain all of these different configurations and designs.
Aside from the higher cost, conventional steel links are heavy and tend to degrade the performance and longevity of the wiper system. This can be better understood when one considers that a typical wiper changes directions as much as 130 times per minute. Inertia is therefore a factor. Acceleration and deceleration forces exert loads on the wiper linkage, especially at the connecting points, and these loads add to the loads required to move the arms and blades back and forth across the windshield. Moreover, each time the direction of motion changes there are forces transmitted back to the motor which result in back and forth thrusting forces being applied to the motor armature. This can become a source of noise and wear as the armature bounces against the thrusting surface.
Therefore, it would be desirable to reduce the weight of the linkage as much as possible, since this would lower the inertia, reduce the load placed on the actuator motor and minimize noise and wear.
While reduction of weight is desirable for the reasons set forth above, simply making the linkage thinner is not desirable, since strength would be sacrificed. Strength is quite important, since the wiper system must function not only on rainy days, but also on snowy and icy days. On snowy and icy days considerably greater strength is required since the wipers are used to move heavy amounts of snow or to break the wiper blades free of an icing condition.
The present invention provides a fresh approach to the design and manufacture of windshield wiper linkage which results in a linkage that is considerably lighter than conventional linkage and with the strength equivalent to or better than conventional linkage. The linkage employs an elongated hollow extrusion of aluminum or other suitable lightweight material which is open at at least one end to receive a coupling member which has a tongue portion disposed in the open end of the extruded member. The coupling member defines a pivot-forming structure for connection to the pivot linkage of the wiper.
In the presently preferred embodiment the extruded member is fabricated from aluminum and is formed with radius interior corners to provide extra strength. The coupling member of the presently preferred embodiment is an injection molded plastic material which is readily and economically manufactured and which is exhibits good pivot wear characteristics. The presently preferred pivot structure is a ball and socket arrangement.
The present invention also provides a method of manufacturing the wiper linkage whereby an elongated member is extruded and cut to suitable length leaving at least one open end. A coupling member, preferably of molded plastic, is formed and inserted into the open end of the elongated member. The coupling member is formed with a tongue which is inserted into the open end of the elongated member. The elongated member is then crimped or otherwise suitably formed to form a mechanical engagement with the tongue. This secures the coupling member to the elongated member. The coupling member can be formed to include a pivot-forming socket and the linkage is then suitably secured to the pivot assembly of the wiper by snap-fit engagement of the pivot assembly ball into the pivot-forming socket.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings.